The present invention relates to a seal structure suitable for an electronic control device such as engine control unit or automatic transmission control unit. Hereinafter, the terms “upper” and “lower” are used with respect to the height (thickness) direction of the electronic control device; and the terms “front” and “rear” are used with respect to the insertion direction of a connector of the electronic control device for connection to an external device. It should however be noted that these terms are used for illustration purposes and are not intended to limit the scope of the present invention.
Japanese Laid-Open Patent Publication No. 2014-049702 discloses a seal structure for an electronic control device such as engine control unit or automatic transmission control unit. The electronic control device includes a housing having a base member and a cover member fitted on an upper side of the base member, a circuit board accommodated in an inner space of the housing and a connector attached to a front end side of the circuit board and exposed through a front opening window between the base and cover members of the housing.
A first connector seal surface is formed on an upper surface of a front end portion of the base member in a width direction of the connector. A substantially U-like shaped continuous seal groove is formed in an upper surface of an outer peripheral end portion other than the front end portion of the base member. Both end regions of the seal groove are bent inwardly in a substantially L-like shape and extend continuously to longitudinal end regions of the first connector seal surface.
On the other hand, a front end portion of the cover member is expanded in a thickness direction of the connector such that the opening window is defined between the front end portion of the base member and the expanded front end portion of the cover member. A substantially U-like shaped continuous seal protrusion is formed on a lower surface of an outer peripheral end portion other than the expanded front end portion of the cover member.
The seal protrusion is engaged in the seal groove, with a sealant filled in a clearance between the seal protrusion and the seal groove, so as to provide a so-called protrusion-groove seal between the base member and the cover member. In this protrusion-groove seal, the sealant can ensure its seal length by engagement between the seal protrusion and the seal groove.
The connector is held between the front end portion of the base member and the expanded front end portion of the cover member, with a first connector seal material (elongated seal tape) arranged between the first connector seal surface of the base member and a lower surface of the connector and a second connector seal material (elongated seal tape) arranged between a lower and inner lateral surface of the expanded front end portion of the cover member and an upper and outer lateral surfaces of the connector, so as to provide a so-called plane seal between the connector and the housing.
Further, fixing holes are formed in four peripheral corners of the base member; and fixing protrusions are formed on four peripheral corners of the cover member. By engagement of the fixing protrusions in the fixing holes, the cover member is fixed in position on the base member. The cover member is then secured to the base member by screws.